Author: Anila B. Elliott, MD - C.S. Mott Children’s Hospital - University of Michigan
In children with congenital heart disease (CHD) supported with extracorporeal membrane oxygenation (ECMO), which of the following factors is most consistently associated with both high complication rates and worse outcomes?
EXPLANATION
A small but high-risk subset of patients with CHD require ECMO for cardiac arrest, low cardiac output syndrome or failure to wean from cardiopulmonary bypass. While short-term ECMO can be utilized as a bridge to recovery, transplant, or more durable circulatory support, the need for prolonged ECMO support has a significant impact on morbidity and mortality1,2,3. A recent study looking at outcomes of almost 10,000 CHD patients showed that about 2% required ECMO, with overall survival around 50% for the ECMO cohort1.The risk of needing ECMO is higher in younger patients (especially infants), those weighing less than 3kg, and patients with heart failure, acute kidney injury, rhythm disturbances, or complex anatomy2,4.
For those who require ECMO, several factors are associated with worse outcomes, including severity of illness at cannulation, reflected by high pre-ECMO lactate, end-organ dysfunction such as acute kidney injury, inadequate anatomical repair, complex physiology including those with single ventricle anatomy, and duration of ECMO1. Prolonged duration of ECMO of 6 days or more and renal failure requiring continuous renal replacement therapy (CRRT) were shown to be independently associated with increased mortality in the CHD population1,5.
Bivalirudin, a direct thrombin inhibitor, is being used more frequently as the primary anticoagulant in pediatric mechanical circulatory support, especially in those with implanted Berlin EXCOR ventricular assist devices. Evidence for its routine use as the primary anticoagulant on ECMO is more limited, but there is increasing evidence showing promising improvement in bleeding and thrombotic complications6 when compared to heparin.
Since worse outcomes on ECMO are linked to greater illness severity at cannulation, reflected by elevated pre-ECMO lactate, prolonged duration of ECMO (over 6 days), and with younger and smaller patients (infants less than 3 kg), while bivalirudin is associated with fewer thrombotic complications in patients on mechanical support,6 and may therefore mitigate risk on ECMO. Thus, choice C, “elevated pre-ECMO lactate" is the correct answer.
REFERENCES
1. Schaeffer T, Hayat S, Matsubara M, et al. Early outcomes of extracorporeal membrane oxygenation in congenital heart surgery. Eur J Cardiothorac Surg. Published online March 14, 2026. doi:10.1093/ejcts/ezag123
2. Aiello S, Loomba RS. Factors Associated with the Need for, and the Impact of, Extracorporeal Membrane Oxygenation in Children with Congenital Heart Disease during Admissions for Cardiac Surgery. Children (Basel). 2017;4(11):101. Published 2017 Nov 22. doi:10.3390/children4110101
3. Faheem MSB, Khan AA, Cheema S, Akhtar M, Ashraf DA. Importance of extracorporeal membrane oxygenation (ECMO) in congenital heart diseases: a systematic review. Egypt Heart J. 2025;77(1):70. Published 2025 Jul 11. doi:10.1186/s43044-025-00667-7
4. Bhat P, Hirsch JC, Gelehrter S, et al. Outcomes of infants weighing three kilograms or less requiring extracorporeal membrane oxygenation after cardiac surgery. Ann Thorac Surg. 2013;95(2):656-661. doi:10.1016/j.athoracsur.2012.06.041
5. Kuraim GA, Garros D, Ryerson L, et al. Predictors and outcomes of early post-operative veno-arterial extracorporeal membrane oxygenation following infant cardiac surgery. J Intensive Care. 2018;6:56. Published 2018 Sep 3. doi:10.1186/s40560-018-0326-4
6. Giorni C, Cantarutti N, Olimpieri A, et al. Heparin Versus Bivalirudin in Pediatric Patients Assisted With Mechanical Circulatory Support: A Retrospective Before-and-after Study. J Cardiothorac Vasc Anesth. 2025;39(5):1242-1249. doi:10.1053/j.jvca.2025.01.041